1. Field of the Invention
This invention relates to a centrifugal separator, and more particularly to a centrifugal separator which is adapted to feed stock liquid to a basket to separate the liquid into solid matter component or cake and liquid component.
2. Field of the Invention
Conventionally, a closed-type centrifugal separator has been widely used for the preparation of pharmaceutical material and the like, because it avoids the inclusion of injurious materials such as impurities, bacteria and the like therein.
A centrifugal separator is generally adapted to subject stock material to a liquid-removing or drainage treatment, scrape solid matter component deposited as a layer on the inner periphery of a basket by means of a scraper and discharge the scraped solid matter to the exterior of the basket. The scraper comprises a drive shaft provided to be axially movable in the basket, a scraper blade mounted on the drive shaft and a drive mechanism for rotating the scraper blade about the drive shaft and moving the scraper blade in the axial direction of the basket, and is adapted to be actuated to carry out scraping of the solid matter. For example, the scraper is adapted to carry out the scraping operation in a manner to pivotally move the scraper blade to the periphery of the basket to allow the scraper blade to enter the solid matter layer while rotating the basket at a low speed and concurrently gradually downwardly move the scraper blade along the axial direction of the basket, to thereby scrape the solid matter.
Although an open-type centrifugal separator is adapted to discharge the so-scraped solid matter through an opening provided at the lower portion of the basket, the closed-type centrifugal separator which is not provided with such an opening is required to suck the solid matter collected in the basket into a solid matter discharge pipe connected to a suction pump and discharge the solid matter therethrough to the exterior of the basket.
As one of the closed-type centrifugal separators adapted to discharge the solid matter using such a solid matter discharge pipe, a centrifugal separator is proposed which is constructed in a manner such that the scraper blade is communicated at the distal end thereof with a suction port of the the solid matter discharge pipe to suck and discharge the scraped solid matter upon scraping of the scraper blade. However, the centrifugal separator has a disadvantage that it fails to suck all the scraped solid matter, so that a considerable part of the scraped solid matter falls on the bottom of the basket to deposit thereon. The deposition of the solid matter on the bottom of the basket above a level causes the scraper blade to abut against the deposited solid matter to be prevented from further lowering, resulting in the further scraping operation not being carried out. This causes the solid matter remaining in the basket to be increased to lead to an increase in the solid matter uselessly wasted.
In order to eliminate such a problem, it is considered to insert another solid matter discharge pipe into the basket to discharge the solid matter deposited on the lower portion of the basket by suction. Unfortunately, this causes the structure of the centrifugal separator to be highly complicated. Also, the conventional centrifugal separator is generally constructed in a manner such that the overall bottom of the basket is of flat form; accordingly, it is still less likely to discharge all the solid matter deposited on the bottom of the basket in spite of use of the further discharge pipe. Thus, the problem that a considerable amount of the solid matter remains in the basket is still not solved.
Accordingly. it is highly desirable to develop a centrifugal separator which is capable of efficiently carrying out the discharge of substantially all scraped solid matter with a simple structure.